* {
  margin: 0;
  padding: 0;
}

html,
body {
  height: 100%;
  width: 100%;
}

div {
  height: 300px;
  width: 300px;
  border-radius: 50%;
  margin: 50px auto;
  background-color: #409EFF;
  color: white;
  font-size: 48px;
  text-align: center;
  line-height: 300px;
  position: relative;
  cursor: pointer;
}

div>h1 {
  font-family: '楷体';
  font-size: 30px;
}

div p {
  height: 260px;
  width: 260px;
  border-radius: 50%;
  background-image: url(img/1.jpg);
  border: 20px solid rgba(255, 255, 255, .5);
  background-origin: border-box;
  position: absolute;
  top: 0;
  transition: transform 1.5s linear;
  transform-origin: left center;
}

div:hover p {
  transform: rotateY(180deg);
}